Johann Karl Burckhardt (30 April 1773 – 22 June 1825) was a German-born

astronomer An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, natural satellite, moons, comets and galaxy, galax ...

and

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, mathematical structure, structure, space, Mathematica ...

. He later became a naturalized French citizen and became known as Jean Charles Burckhardt. He is remembered in particular for his work in fundamental astronomy, and for his

lunar theory Lunar theory attempts to account for the motions of the Moon. There are many small variations (or perturbation (astronomy), perturbations) in the Moon's motion, and many attempts have been made to account for them. After centuries of being problema ...

, which was in widespread use for the construction of navigational ephemerides of the Moon for much of the first half of the nineteenth century.

Life and career

Burckhardt was born in

Leipzig Leipzig (, ; ; Upper Saxon: ; ) is the most populous city in the States of Germany, German state of Saxony. The city has a population of 628,718 inhabitants as of 2023. It is the List of cities in Germany by population, eighth-largest city in Ge ...

, where he studied

mathematics Mathematics is a field of study that discovers and organizes methods, Mathematical theory, theories and theorems that are developed and Mathematical proof, proved for the needs of empirical sciences and mathematics itself. There are many ar ...

and

astronomy Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest includ ...

. Later he became an assistant at the

Gotha Observatory Gotha Observatory (''Seeberg Observatory'', ''Sternwarte Gotha'' or ''Seeberg-Sternwarte'') was a German astronomical observatory located on Seeberg hill near Gotha, Thuringia, Germany. Initially the observatory was dedicated to astrometry, geodet ...

and studied under

Franz Xaver von Zach Baron Franz Xaver von Zach (''Franz Xaver Freiherr von Zach''; 4 June 1754 – 2 September 1832) was an Austrian astronomer born at Pest, Hungary (now Budapest in Hungary). Biography Zach studied physics at the Royal University of Pest, and ...

. On von Zach's recommendation, he joined the observatory of the

École militaire École or Ecole may refer to: * an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing in région Île-de-France * Éco ...

in Paris, then directed by

Jérôme Lalande Joseph Jérôme Lefrançois de Lalande (; 11 July 1732 – 4April 1807) was a French astronomer, freemason and writer. He is known for having estimated a precise value of the astronomical unit (the distance from the Earth to the Sun) using measu ...

. He was appointed as ''astronomer-adjoint'' to the ''

Bureau des Longitudes __NOTOC__ The ''Bureau des Longitudes'' () is a French scientific institution, founded by decree of 25 June 1795 and charged with the improvement of nautical navigation, standardisation of time-keeping, geodesy and astronomical observation. Durin ...

'' and received his letters of French naturalization as a

French French may refer to: * Something of, from, or related to France ** French language, which originated in France ** French people, a nation and ethnic group ** French cuisine, cooking traditions and practices Arts and media * The French (band), ...

citizen in 1799, and was elected to the '' L'Institut National des Sciences et des Arts'' in 1804. After Lalande's death in 1807, Burckhardt became director of the observatory at the

. He was elected a Foreign Honorary Member of the

American Academy of Arts and Sciences The American Academy of Arts and Sciences (The Academy) is one of the oldest learned societies in the United States. It was founded in 1780 during the American Revolution by John Adams, John Hancock, James Bowdoin, Andrew Oliver, and other ...

in 1822.

Scientific work

Burckhardt carried out extensive studies on the

orbit In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...

s of

comet A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...

s, and his study of a comet of 1770 had initially gained him some professional reputation. In 1812 he published an improved

, after that of

Pierre-Simon Laplace Pierre-Simon, Marquis de Laplace (; ; 23 March 1749 – 5 March 1827) was a French polymath, a scholar whose work has been instrumental in the fields of physics, astronomy, mathematics, engineering, statistics, and philosophy. He summariz ...

. Burckhardt's lunar tables appear to have been the first to be based on a

least squares The method of least squares is a mathematical optimization technique that aims to determine the best fit function by minimizing the sum of the squares of the differences between the observed values and the predicted values of the model. The me ...

adjustment of the coefficients to selected lunar observations, of which about 4000 were used; and a committee of the

(consisting of

Laplace Pierre-Simon, Marquis de Laplace (; ; 23 March 1749 – 5 March 1827) was a French polymath, a scholar whose work has been instrumental in the fields of physics, astronomy, mathematics, engineering, statistics, and philosophy. He summariz ...

Delambre Jean Baptiste Joseph, chevalier Delambre (19 September 1749 – 19 August 1822) was a French mathematician, astronomer, historian of astronomy, and geodesist. He was also director of the Paris Observatory, and author of well-known books on th ...

, Bouvard, Arago and Poisson) concluded after an early form of sum-of-squares analysis that Burckhardt's tables improved on those of Bürg. Accordingly, they enjoyed for some decades a substantial reputation as the most accurate available. They were officially used for computing the lunar

ephemerides In astronomy and celestial navigation, an ephemeris (; ; , ) is a book with tables that gives the trajectory of naturally occurring astronomical objects and artificial satellites in the sky, i.e., the position (and possibly velocity) over time. ...

the Nautical Almanac ''The Nautical Almanac'' has been the familiar name for a series of official British almanacs published under various titles since the first issue of ''The Nautical Almanac and Astronomical Ephemeris'', for 1767: this was the first nautical alm ...

from 1821 to 1861 (but they were superseded in part, as from 1856, for computing the lunar horizontal parallax, by improved tables due to J C Adams). Burckhardt's tables were eventually replaced altogether, for issues of the Nautical Almanac for 1862 and thereafter, by new computations based on P A Hansen's more comprehensive

.Explanatory Supplement to the Astronomical Ephemeris, (London, 1961), sect. 7B, pp. 177–8. The crater

Burckhardt The Burckhardt family alternatively also (de) Bourcard (in French) is a family of the Basel patriciate, descended from Christoph (Stoffel) Burckhardt (1490–1578), a merchant in cloth and silk originally from Münstertal, Black Forest, who rece ...

on the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

is named after him.

References

Bibliography

* Burckhardt, 1794, ''Methodus combinatorio-analytica, evolvendis fractionum continuarum valoribus maxime idonea'', Leipzig. {{DEFAULTSORT:Burckhardt, Johann Karl 19th-century French astronomers 18th-century German astronomers 1773 births 1825 deaths Fellows of the American Academy of Arts and Sciences Members of the French Academy of Sciences Scientists from Leipzig 18th-century German mathematicians 19th-century French mathematicians